Compressor unloading valve mechanism



March 11, 1941; Y mcK 2,234,488 pou'rnzssoannmnpme VALVE uscmmxsu- FiledNov. is, 1939 3 -2 Sheets-Sheet x INVENTOR.

ATTORNEY B. DICK connissson' momma VALVE uscmrsu Filed Nov. 8, 19:59 2Sh eets-Sheet 2- INVENTOR RNS DICK rronamzwr PatentedMar, 11, 1941 BurnsDick, Ferguson, Ma,

Electric Corporation, tion of Delaware assignor to Warner St. Louis,Mo., a corpora- Application November 8, 1939, Serial No. 303,378

5 Claims. My invention relates to compressors and more particularly tovalve mechanism for unloading the compressor under certain conditions.

One of the objects of my invention is to pro- 5 vide an improved valvemechanism for automatically unloading a compressor when the fluidcompressed thereby and discharged into a receiver is a predeterminedvalue.

Another and more specific object of my in- 1 vention is to embodyelectrical-operated control means in the compressor unloading valvemechanism to thereby facilitate the installation of .the control valveswhich form a part of the' r mechanism and also lower the cost ofmanufacture.

Other objects of my invention will become apparent from the followingdescription taken in connection with the accompanying drawings in whichFigure 1 is a view, partly in section, of a compressor having associatedtherewith an unloading valve mechanism embodying my invention and Figure2 is a view, partly in section, showing a modified unloading valvemechanism.

Referring to the drawings in detail, the rotary compressor is of knownconstruction and comprises a stator i having eccentrically mountedtherein a rotor 2 secured to a drive shaft 3 jour naled in the endplates 4 and-5. The rotor 2 is provided with a plurality of spaced slotsextending in an axial'direction in which are mounted reciprocable bladesI (one only being shown) biased outwardly into engagement with the innersurtace'of the stator by springs 8. The end plate 41s provided with anintake passage 9 and the end plate with an outlet passage i0. Secured tothe end plate 5 is anoil reservoir or dome II which contains oil for thepurpose of lubricating the compressor. In the construction shown theshaft '3 of the compressondrives an oil p mpJl to pump oil from thethrough'passagefl and discharge it I4 through the opening II. The oil isfree toin the well the compressed air. The discharge port l0 hasasociated therewith a check valve 20 for preventing any of thecompressed air from returning to the compressor. The oil domecommunicates with the compressed air receiver or tank 2! by a conduit 22and a check valve 23 prevents return of compressed air to the dome. Thecompressed air may be used for any purpose desired,

as for example, the actuation of vehicle brakes.

In the type 01' compressor just described the compressor is generallyautomatically unloaded by shutting oil the intake when the receiver torthe compressed air discharged by the compressor reaches a predeterminedvalue and again allowed to compress air when the compressed air in thereceiver falls to a given pressure below the pre-' determined va1ue.,With such an arrangement, d that when the compressor it has beendiscovere is unloaded an excess amount of oil may be fed to thecompressor and cause it to become choked" because oi the compressed airacting upon the oil and forcing it into the compressor. It has also beendiscovered that the shutting off of the compressor by closing the intakedoes 'not cause the compressor to run idle .since the compressor stilloperates to compress the air remaining in the compressor which may bepartially discharged into the oil dome against the compressed airalready therein or, if this is not accomplished due to insuihcient airto com; press, recirculated and recompressed continuously. By thecompressor being partially under load and performing work, it willcontinue to generate heat and use power, notwithstanding no additionalcompressed air is being added to the receiver All of these undesirableoperating tea.-

tures present when the compressor intake is shut hody of oil into a wellflow through the passage IS in. shaft 3 and then into. the compressor byway of the} keyway ll to thus provide lubrication for the movable partsof the compressor. Inorder that the oil may be forced into thecompressor under pressure during operation of the compressor, the

' body of-oil in theoil dome is caused to be sub- 50 iect to the fluidunder" pressure discharged from the compressor. is accomplished byhaving the discharge port i| connec which extends above the oil rator l4removes any excess discharged from the compres line. An oil sepaoilwhich may be sor together with ted to a pipe ll oil can be eliminated toa large. extent by also unloadingthe oil'dome at the same time theintake is shut oil. With the air in the oil dome under atmosphericpressure, the oil forced into the compressor will be'reduced and the airand oil being circulated in the compressor will be free to be dischargedinto the oil dome against atmospheric pressure instead of against com-"Pressed air.- A superior operating compressor results which will requireless power to operate when no air isrequired to be compressedQ Also thecompressor will operate at a much cooler temperature, less oil willbeused, and the life of the compressor extended. My improved valvemechanism for shutting off the intake and opening the oil reservoir toatmosphere coinprlsesa casing 24' provide with intercommunicatingpassages 25 and- 2 the former being connected to the inlet passage 9 andthe latter to the atmosphere through the 'air cleaner 21. Associatedwith passage 29 is a valve seat 29 and cooperating therewith is a valvemember 29 positioned in an enlarged chamber 39 between the passages 25and 29. The valve member 29 is normally biased to an open position by alight spring 3|.

The casing of the valve mechanism is also provided with a chamber 32which is connected to the top of the oil reservoir or dome II by aconduit 33. The chamber 32 communicates with passage 29 by means of apassage 34 which has associated with its end a valve seat 39 andcooperating with this seat is a valve element 39 positioned in chamber32 and normally held upon the seat by spring 31. Between the chamber 32and the passage 25 is a bore 39 in which is guided an extension 39carried by the valve member 29. g The extension is of such length thatwhen the valve member 29 is in open position, the valve member 39 willbe held seated by its spring and when the valve member 29 is moved toclosed position, the extension 39 will force the valve member off itsseat and place chamber 32 (and also the oil reservoir II) incommunication with atmosphere through passage 34.

In order that the valve member 29 may be moved to closedposition and thevalve member 39 to open posit on when the pressure in the receiver 2| isa predetermined value-there is provided a solenoid 49, the winding 4| ofwhich is connected to the valve member 29. One-end of the winding isconnected to ground by a conductor 43 and the other end is connected bya conductor 44 to one side of the battery 49, the other side beingconnected to ground by conductors 49 and 41 through a pressure-operatedswitch 49. This switch comprises a fixed contact 49 connected totheconductor 41 and a movable contact 59 connected to the conductor 49. Themovable contact is carried on a diaphragm 9| which is biased by a spring52 to a position where the contacts 49 and 99 will be normallydisengaged. The diaphragm 9| forms with the housing 93 of the switch, achamber 54 which is in constant communication with the compressed fluidin the receiver 2| by a conduit 99. Spring 92 for the switch is of suchstrength that it will maintain the contacts separated untilapredetermined pressure-is present in the receiver of the chamber. 94."Ibrr the purpose of this description, this pressure is considered as onehundred pounds per square inch.

When the compressor is operating, the parts of the valve mechanism andthe switch are in the position shown in Figure 1. Under these conditionsthe valve element 29 will. be open and the valve member 39 will beclosed. This will permit air to oe drawn into the compressor where it iscompressed and forced out through the check valve 29 into the oilreservoir II and then through the check valve 23 into the receiver' 2|.when the compressor has operated 65 sumciently to bring the pressure inthe receiver to the assumed predetermined'value of one hundred poundsper square inch, the contacts 49 and 99 of the switch will be closed bymovement of the diaphragm against the action'of springv 92.

Closing of the switch will energize the solenoid 49 and cause itsarmature to move the valve member 23 to theleft, thereby shutting oi!the intake e to the compressor. Simultaneously with (the movement of thevalve member 29 to closed 7 position, the valve member 39 willbe movedof! 'outlet valve 29 off its seat against any built-up its seat andthereby place the oil reservoir in communication with .atmosphere andcause the pressure in the reservoir to drop to atmospheric pressure. Thecompressor now-' will be substantially completely unloaded. Any airwhich may 6 be in the compressor will be easily forced out through thecheck valve 29 into the oil dome and from there into atmosphere since itis not necessary for the air being compressed to move the pressure.There may be a slight leakage of air in the compressor around theextension 39 but this air will be easily circulated through thecompressor forced out through the outlet valve with very littlecompressing operation. The connecting of the oil reservoir to atmospherealso results in placing the oil in the oil well i4 under atmosphericpressure and the only oil which will flow into the compressor will bethat which flows'under the action of gravity and that which is pulled 20in as a result of sub-atmospheric pressure in portions of thecompressor. The flow of oil will be so decreased that the compressorwill not tend to choke" up as would be the case if the intake were shutoflf and the pressure in the oil dome 25 not relieved. Since thecompressor is now running idle and not performing any compressingoperation, the power necessary to turn the rotor k is a minimum and theheat being generated by the compressor is also a minimum. Consequently,an

the compressor will have an opportunity to cool as will also the oil inthe reservoir. The result is a more emciently operating compressor andone in which the life is considerably extended When fluid under pressureis used ,irom the- 35 air receiver and the pressure therein drops to'such a value that spring 52 of the switch can open the contacts thereof,the solenoid will be. de-energized and 'the valve member 29 moved to anopen position by spring 39. Simultaneously with the opening of the valvemember 29, the valve member '39 will be closed, thereby again sealingthe oil reservoir. The compressor can now begin to compress air andagain force it into the air receiver to thereby bring the pressure of 5the air in the receiver up to the predetermined 1 value of one hundredpounds per square inch.

In Figure 2 there is shown a modified valve mechanism for shutting offthe intake of the compressor and venting the oil'reservoirto at- 50'mosphere. In theflgure the parts similar to those disclosed in Figure 1have the same referby a spring 93, the tension ofwhich is adjustable bythe nut 94. The valve member 92 is provided. with an extension 99 whichis guided in a sleeve 95 99 carried by a member 91 of insulatingmaterial. The extension 99 abuts against a diaphragm 99 which is held insealed engagement with the valve casing by a cap 99. The chamber 19above the diaphragm is placed in communication with the 7 airreceiver bya conduit II.

The oil dome II is provided with a vent passage I2 which is connected toatmosphere through the air cleaner by a conduit I3. Associated with thevent passage is a valve seat 14 ll 15 ductor 82.

, 62 will not be moved to closed 25 hundred pounds per square inchpressure is present in the air receiver and also chamber above 50thereby sealing the oil 65 trolling bot and cooperating therewith is avalve member '15 having connected with its stem a plunger I6 5 to holdthe valve member seated. One end of the winding 19 of the solenoid isgrounded and the other end is connected bya conductor 80 through abattery ill to the valve member 82 which is made of conductingmaterialand forms 10 one of the contacts of a switch. The other contact for thisswitch is the valve seat 6| formed on the valve casing which is alsomade-oi conducting material. The circuit is completed by connecting thevalve casing to ground-by a con- In order that the valve 62 may becompletely insulated in the valve casi an insulating member 83 isinterposed between the spring I3 and the valve element. As alreadymentioned, the guide sleeve 66 is insulated from 20 the casing by themember 61.

'When the compressor is operating, the parts are in the position shownin Figure 2. The tension of spring 53 is such that the valve memberposition until one the diaphragm. When the air receiver reaches thepressure of one hundred pounds per square inch, the valve member 62 willbe moved to closed position and shut ofi the intake of the compressor.The suction of the compressor ;will now be eflective to assist theholding'of the valve member on its seat. As the valve member 62engages-the seat, theelectrical circuit is closed.

The closing of the switch energizes the solenoid l1 and causes theplunger 18 to move the valve member 15 oil its seat, thereby placing theoil reservoir in communication with the atmosphere and dropping thepressure therein. The

compressor will then be substantially completely unloaded.

When compressed air in the receiver is used and the pressure thereindrops to such a value that the spring 83 can again open the valve member62 against the Iorces tending to hold it closed,

the compressor will again begin to operate to compress air. As the valvemember 62 is unseated, the electrical circuitwill be broken and.

the valve member 15 closed by the spring 18, reservoir and resulting inthe compressed air discharged therein flowing directly to the airreceiver.

By employing electrical means for controlling I either one or both ofthe valves of. the unloading 5 valve mechanism, installation thereof isfacilitated. In the construction shown in Figure 1, the switch can beplaced in any convenient place and no problem is employed in connectingthe switch in circuit with the solenoid. In 'the con- 5 struction shownin Figure 2, the valve for vent-,

ing the oil reservoir can be made separate from the intake shutit valveand mounted at-a distance therei'rom directly on the reservoir casing, Asingle fluidmotor can .be employed for. conlg valves, thus minimizingthe cost. Being aw re oi the possibility of other modi'- flcations'inthe particular'structures herein described without departing from thefundamental principles oi my invention, I do not intend that their scopebe limited except as' set forth by*the 1 appended claims.

Having fully described my invention, what I claim as new and desire tosecure by letters Patent oithe United States is:

- placing the discharge port in communication with for placing thedischarge 'with the atmosphere, at the intake-valve when and a movablevalve- 1. In compressed air storage apparatus comprising a receiver andan air compressor 'provided with intake and discharge ports, a normallyopen intake valve, a normally closed valve for placing the dischargeportin communication with the atmosphere, and automatically operablemeans for closing the intake valve and substantially, simultaneouslyopening the second named valve whenthe fluid pressure in the receiverreaches a predetermined value, said means comprising a solenoid forcontrolling at least one of said valves, the solenoid, and a switch:caused to be closed when the pressure in the receiver reaches saidpredetermined value. g

2. In compressed air storage apparatus comprising a receiver and an aircompressor provided with intake and discharge ports, a normally openintake valve, a normally closed valve for an electrical circuit for theatmosphere, means for operatively connecting the valves together so thatnamed valve isclosed the second named valve will be open, a solenoid forcontrolling said valves, an electrical circuit including a switch forcans-- ing operation of the solenoid, and means for. closing the switchwhen the pressure in the receiver is a predetermined value. 3. Incompressed air storage apparatus comprising a receiver and an aircompressor provided with intake and discharge ports, an intake valveresiliently biased to an open position, a second valve resilientlybiased to closed position and capable of connecting the discharge portto atmosphere, the movable elements of said valves being in axialalignment, a rod operatively connecting the movable valve elements, asolenoid for closing th intake valve and by means oi the rod cause thesecond valve to be open, and' when the first an electrical circuit forenergizing the solenoid 40 including a normally open switch, .and afluid motor connected to close the switch when the receiver pressurereaches a predetermined value.

4. In compressed air storage apparatus comprising a receiver and videdwith intake and discharge ports, a normally open intake valve,

a normally closed valve port in communication fluid motor for closingceiver reaches apredetermined value, a solenoid J for opening the secondnamed valve, and an electrical circuit including a switch for energizingthe solenoid, said switch being so associated with the fluid motor thatit position by the fluid motor simultaneously with the closing of thefirst named valve. 5. In compressed air storage apparatus comprising-areceiver andan air compressor providan air compressor pro- 45' thepressure in the re-l will be moved to closed ed with intake anddischarge ports, anormally open intake valve, said valve comprising aseat element made of electrical conductive materialfla normally closedvalve' for placing the discharge port in communication with theatmosphere, a intake valve by seating the movable'valve element when thepressure in the receiver reaches a predeterminedvalue, va solenoid foropening the second named valve and an electrical circuit for seat andthe movable valve element as a switch.

BURNS DICK.

fluid motor tor closing the energizing the solenoid and including thevalve 7

